Gas turbine engines often utilize rotary fuel injectors or "slingers" to deliver fuel to the combustion chamber of the engine. Fuel flows axially through the main shaft of the engine and is thereafter injected radially into the combustion chamber thereof through nozzles that rotate with the shaft. The present invention takes advantage of the presence of pressurized fuel internally of the engine shaft and is based on the premise that conventional jet fuels are capable of providing satisfactory lubrication of anti-friction bearings. The use of fuel as a lubricant eliminates the requirement for an independent lubrication system comprising, for example, oil mist generators, oil pumps, oil sumps, and associated plumbing.
However, a significant disadvantage heretofore associated with the use of fuel as a lubricant has been the difficulty in producing a pressure differential across the bearing sufficient to induce flow of fuel therethrough. It is known to discharge pressurized fuel into the atmosphere to produce the desired pressure differential across the bearing but loss of fuel and pollution caused by the discharged fuel is unacceptable.
The present invention removes the aforesaid objection to the use of fuel as a lubricant by inducing flow of fuel through the bearing by an inherent centrifugal pumping action and thereafter recapturing the fuel.